This invention relates to an iron golf club set consisting, as a unit, of a long iron golf club group, a middle iron golf club group and a short iron golf club group.
Generally, an iron golf club set consists of at least ten iron golf clubs, i.e. nine iron golf clubs having the club numbers of #1 to #9 and one iron golf club of a pitching wedge PW, as a unit. These golf clubs are classified in accordance with their club length. The golf clubs of the club numbers #1 to #3 are referred to as "long iron golf clubs", those of #4 to #6 are referred to as "middle iron golf clubs" and those of #7 to #9 and the pitching wedge iron golf club PW are referred to as "short iron golf clubs". The long iron golf clubs are used in order to obtain a long flying distance of a ball or "yardage", the middle iron golf clubs are used to obtain a middle flying distance and the short iron golf clubs, to obtain a short flying distance.
Conventionally, the iron golf clubs constituting the iron golf club set are arranged in such a way that when the three groups of golf clubs, that is, the long iron golf clubs I.sub.L, the middle iron golf clubs I.sub.M and the short iron golf clubs I.sub.S, are arranged in accordance with the club numbers with predetermined gaps between them, their club length l becomes progressively shorter when the club number # becomes greater. These iron golf clubs are characterized in that directionality of the hit ball is more accurate than in the case of wood golf clubs, and their club length is set to be shorter than that of the wood golf clubs. Therefore, those golf players such as amateurs who cannot gain a large distance or yardage use a wood golf club without using the long iron golf club when they wish to gain a large yardage on a fairway and cannot therefore utilize excellent directionality of the hit ball that the iron golf club has.
In order to solve the problem described above, the inventors of the present invention previously proposed in Japanese Utility Model Application Kokai Publication No. 62-172467, wherein the change ratio of the club length l from the long iron golf club I.sub.L to the intermediate member of the middle iron golf clubs I.sub.M is made greater than that in the prior art example as shown in FIG. 5 and also in Japanese Utility Model Application Kokai Publication No. 62-174556, wherein a large step is given to the change of the club length l at the intermediate part of the middle iron golf club group I.sub.M and the club length l on the side of the long iron golf club group I.sub.L is made drastically greater than that in the prior art example, as shown in FIG. 5. According to the former, however, the pitch difference of the club length between the golf clubs constituting the long iron golf club group becomes too great and according to the latter, on the other hand, the club length changes remarkably between two specific golf clubs at the intermediate part of the middle iron golf club group. Accordingly, there occurs the problem that the relation between the feel at the time of swing and the flying distance of the hit ball is likely to deviate between both golf clubs having such a great difference of the club length.